Stearoyl CoA desaturases (SCD's) are Δ9 fatty acid desaturases. The mammalian enzymes are localized to the endoplasmic reticulum and require molecular O2 and NADH to desaturate saturated fatty acids at the Δ9 position and generate monounsaturated fatty acids and water in the process. The primary substrates for these enzymes are the acyl-CoA derivatives of stearic (C18) and palmitic acids (C16) with the major reaction being the conversion of stearic acid to oleate (C18:1). Depending on the species, 2-4 highly homologous isoforms of SCD exist differing primarily in tissue distribution.
The best characterized SCD isozyme is SCD1 which is primarily found in liver, adipose and skeletal muscle. Deletion, mutation or inhibition of SCD 1 in mice and rats results in decreased hepatic triglyceride secretion, decreased hepatic steatosis, resistance to weight gain and improvements in insulin sensitivity and glucose uptake (reviewed in Ntambi et al. (2004) Prog Lipid Res 43, 91-104; (2005), Prostaglandins Leukot. Essent. Fatty Acids 73, 35-41; and (2005) Obes. Rev. 6, 169-174. These studies combined with studies in humans showing correlations between surrogates for SCD activity and obesity strongly implicate SCD inhibition as a means to treat obesity, hypertryglyceridemia and associated diseases and co-morbidities. Studies done using antisense oligonucleotide inhibitors have also demonstrated a correlation between SCD activity and obesity and the onset of diet-induced hypatic insulin resistance; see Jiang et al. (2005) J. Clin. Invest. 115:1030-1038G. and Gutíerrez-Juárez et al. (2006) J. Clin. Invest. 116:1686-1695.
The present invention presents compounds that are useful in inhibiting SCD activity and thus regulating lipid levels, especially plasma lipid levels. These compounds are useful in the treatment of SCD-mediated diseases such as diseases related to dyslipidemia and disorders of lipid metabolism, including, but not limited to diseases related to elevated lipid levels, cardiovascular disease, cancer, diabetes, obesity, metabolic syndrome and the like.